Method of silk screen printing

ABSTRACT

A conventional rotary screen is provided with a smooth metal squeegee rod which is used to provide a force for forcing ink through the holes of the patterned screen. Herein the smooth metal rod is provided with a fabric covering or a grooved surface. This squeegee rod structure now applies a nonuniform application of ink to provide a simulated half-tone or marbleized effect to the substrate on which the ink is being applied. This is accomplished now by the use of a single pass and a single color ink.

United States Patent Gra beal Get. 29, 1974 [54] METHOD OF SILK SCREEN PRINTING FOREIGN PATENTS OR APPLICATIONS lnventori Harold Grill/heal, Lancaster, 266,024 11/1968 Austria 101 120 [73] Assignee: Armstrong Cork Company,

Lancaster p Primary ExaminerRobert E. Pulfrey Assistant Examiner-E. H. Eickholt [22] Filed: July 21, 1970 [21] Appl. No: 56,904 [57] ABSTRACT A conventional rotary screen is provided with a 52 us. (:1. 101/129 101/119 Smooth metal Squeegee rod which is used to Provide 51 Int. c1 B 1116 1/12 for fming ink through the holes of the P [58] Field Of Search 101/119 120 124 I29 tamed Herei" the Smooth metal rod P {01/152 153 6 1 6 vided with a fabric covering or a grooved surface. This squeegee rod structure now applies a nonuniform ap- [56] References Cited plication of ink to provide a simulated half-tone or marbleized effect to the substrate on which the ink is UNITED STATES PATENTS being applied. This is accomplished now by the use of 2,4l9,695 4/1947 Shuttleworth et al. lOl/l l6 X a single pass and a Single color ink 2,695,244 ll/l954 Fountain lOl/l70 UX 2,753,794 7/1956 Groak 101/120 1 Claim, 5 Drawing Figures PATENIEDnmze 1914 sum w 2 INVENTOR HAROLD'N- GRAYBEA'L.

ATTORNEY PATENTEDBCI 29 m4 smear z y INVENTOR HAROLD N. GRAYBEAL ATTORNEY METHOD OF SILK SCREEN PRINTING BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is directed to a method for screen printing and, more particularly, to a modified squeegee structure for a screen printer to provide a new printing technique.

2. Description of the Proir Art Conventional rotary screen printing apparatus usually consists of a cylindrical metal pattern screen which runs in contact with the substrate to be printed. A smooth metal rod is placed inside the screen and an electromagnet is located under the substrate. The magnet is used to apply a downward pull on the rod thus forcing the rod against the pattern screen. The rod forces the ink through the holes in the metal pattern screen. The smooth metal rod will apply a uniform application onto or into the substrate, depending upon the porosity of the substrate. The amount of electromagnetic force used will also control the amount of ink applied.

U. S. Pat. No. 2,753,794 discloses a structure which utilizes a squeegee with an irregular surface. The squeegee is provided with a plurality of parallel grooves which extend transverse to the direction of movement of the squeegee. The parallel grooves are ink retaining reservoirs and are used to dispense a controlled quantity of ink. Uniform printing is secured and there is no suggestion and no possibility of obtaining a pattern effect as a result of the squeegee structure disclosed in the above patent.

The squeegee structure disclosed herein provides a method for applying a nonuniform application of ink. Different patterns on the rod will provide for different printed patterns.

SUMMARY OF THE INVENTION The invention involves the providing of the conventional squeegee rod of a rotary screen printer with a pattern which is carved, etched or.somehow applied to the rod surface. The rod now contains areas of various depths and cross sections, and a pattern of ink is deposited dependent upon these areas. The two primary ways of securing a pattern on the squeegee rod are the cutting of the pattern into the surface of the metal rod or the wrapping of the rod with a pattern'effect, for example, a carpet material which has its weave providing a pattern effect. By controlling the type of pattern provided on the rod, a simulated half-tone or marbleized effect can be obtained. These effects can be random and could not necessarily be made by the use of additional pattern screens alone. Due to the various depths of the pattern squeegee rod, slanting sides for instance, a blending tone of color is applied which could not be applied with one screen or several screens.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front schematic view of a conventional rotary screen printer;

FIG. II is a squeegee rod provided with a fabric covermg;

FIG. III is a sample of the pattern effect produced by the squeegee rod of FIG. II;

F IG.IV is a squeegee rod provided with a carved surface; and

FIG. V is a sample of the pattern effect produced by the squeegee rod of FlG.lV.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG.I is a showing of a conventional rotary screen printing apparatus 2. The apparatus consists of a cylindrical metal pattern screen 4 which has a plurality of small holes defining the pattern to be printed. There is a metal rod 6 placed within the screen 4, and this acts as the squeegee to force the ink through the hole structure of the screen onto a substrate 8 which is carried by a conventional conveyer structure 10 past the screen printer. Below the substrate and carrier, there is positioned an electromagnet 12. This magnet applies a force to the metal rod 6 to hold the metal rod in contact with the screen and permits the metal rod 6 to force the ink through the hole structure of the cylindrical metal pattern screen.

FIGS. II and IV disclose two embodiments of the squeegee structure which can be utilized to provide a new technique of printing. Referring now to FIG. II, there is shown a squeegee rod 6 upon which has been placed a fabric material 16. This is a coarse weave fabric which has about nine threads per inch in the weave. Due to the over action and under action of the threads of the weave, the fabric has a roughened surface with the overlying threads providing raised areas and the underlying threads providing depressed areas. When the squeegee rod of FIG. II is utilized in the structure of FIG. I, a unique pattern effect is formed on the substrate. If the substrate is porous, the squeegee rod will force less ink through the rotary screen in those areas where the fabric of the rod has low areas, and more ink is forced through those areas where the fabric pattern of the rod has the raised areas. The porous nature of the substrate will permit absorption of the ink.

FIG. "I is a showing of a structure which was printed by the squeegee rod of FIG. II. The background area is what was printed by the squeegee rod of FIG. II, and it can be seen in the background area that there are spots I8 which appear to be dark relative to a background area 20. The same color ink was printed, and the dark areas are the concentrated ink color while the light background areas are a dilute application of ink; and this permits the background color of the substrate to show througn the dilute ink areas and lighten the color in those areas. Looking back again at FIG. II, it was mentioned that the fabric has raised areas 22 and depressed areas 24. The raised areas 22 provide the dark pattern areas 18 of FIG. III while the depressed areas 24 provide the light areas 20.

Referring now to FIG. IV, there is shown another embodiment of the squeegee rod 6 of FIG. I. Here the smooth surface of the squeegee rod has been carved out to provide an irregular pattern which has depressed areas 26. This pattern could be a geometric repeat type pattern or it could be a randomly disposed pattern. FIG. V shows the results of printing with the squeegee rod of FIG. IV. Here there are dark streak areas 28 and light areas 30. The depressed areas 26 of the rod of FIG. IV tend to contain a large quantity of ink, but little of this large quantity of ink passes through the holes of the rotary metal screen and provides only light ink concentration areas 30. The raised or original surface 32 of the metal rod 6 forces a large quantity of ink through the holes of the rotary screen, and this results in the printing of the high concentration dark areas 28. It is seen that by the use of the random carved-out structure shown in FIG. IV a random veining effect is provided in the structure of FIG. V.

If a nonporous substrate is used, the opposite effect is secured. The raised areas print a small quantity of ink while the depressed areas print a large quantity of ink. With the nonporous substrate, the raised areas can apply only a thin light coat of ink, and excess ink is squeezed off to the sides into the region of the depressed areas. Here in the depressed area, because of low pressure acting on the ink, the ink tends to build up on the substrate as a thick dark layer of ink.

The above effects were secured with a nonpower driven rod. The rod would rotate only due to contact with the screen and its rotation. Different decorative effects can be secured with a power driven rod that rotates faster or slower than the screen.

What is claimed is:

I. In a method of printing a design on a substrate by the use of a metal pattern screen wherein there is provided a metal pattern screen with a decorative pattern provided therein through the use of a hole means in the screen, a means is provided for maintaining a squeegee rod against the surface of the screen to force ink through the screen, and a porous substrate is passed adjacent the screen adjacent the point where the squeegee rod contacts the screen so that ink will be passed through the screen in a predetermined pattern and be applied to the porous substrate, the improvement comprising: providing the surface of the squeegee rod with an irregular pattern of raised areas and depressed areas, printing a porous substrate with the screen using the irregular surface squeegee to provide a pattern effect to the substrate, and causing the irregular surface squeegee rod and porous substrate to coact to provide a pattern effect with the raised area of the rod forcing more ink into a porous substrate while the depressed areas of the rod force less ink into the substrate to give areas of different ink concentration. 

1. In a method of printing a design on a substrate by the use of a metal pattern screen wherein there is provided a metal pattern screen with a decorative pattern provided therein through the use of a hole means in the screen, a means is provided for maintaining a squeegee rod against the surface of the screen to force ink through the screen, and a porous substrate is passed adjacent the screen adjacent the point where the squeegee rod contacts the screen so that ink will be passed through the screen in a predetermined pattern and be applied to the porous substrate, the improvement comprising: providing the surface of the squeegee rod with an irregular pattern of raised areas and depressed areas, printing a porous substrate with the screen using the irregular surface squeegee to provide a pattern effect to the substrate, and causing the irregular surface squeegee rod and porous substrate to coact to provide a pattern effect with the raised area of the rod forcing more ink into a porous substrate while the depressed areas of the rod force less ink into the substrate to give areas of different ink concentration. 